Harmful Mutations

Producing the wrong protein or no protein can be disastrous - especially if that protein is an important enzyme.
If a mutation occurs in reproductive cells, then the offspring may develop abnormally or die at an early stage of their development.
If a mutation occurs in body cells, the mutant cells can sometimes start to multiply in an uncontrolled way and invade other parts of the body. This is cancer.
Haemophilia is an inherited disorder that stops blood from clotting properly - it is caused by a mutated gene.

Helpful Mutations

Occasionally, a different protein produced after a mutation can actually benefit the organism - the new protein is an improvement on the one it was supposed to be.
This gives the organism a survival advantage over the rest of the population. It passes the mutated DNA to its offspring, and they survive better too - soon the mutation becomes common in the population.
This is how natural selection and evolution works.

'No Effect' Mutations

Some mutations aren't harmful or helpful - they don't change to protein being coded for so they have no effect on the organism.
For example, the protein that a mutated gene produces may work just as well as the protein from the non-mutated gene.

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GCSE Biology (Module B3: Living And Growing) Notiz am B3b: Proteins and mutations, erstellt von Carina C am 05/04/2016.